A major focus of the work at the Center for Molecular Medicine and Immunology (CMMI) is immunodiagnosis and immunotherapy of cancer, in patients and in animal models. The individual projects performed at the Center all require flow cytometry support. The Center has a Becton Dickinson FACScan, which was purchased in 1989. The instrument has received continuous heavy usage over the past decade by all investigators at the Center. During the ten years since the FACScan was purchased flow cytometry technology has advanced considerably, making the instrument available today much superior in terms of productivity and performance. In addition, our needs for flow cytometry have grown during this time period. Thus, we are submitting this application for the acquisition of the FACSCaliber Flow Cytometer System with the FACSLoader, an updated flow cytometry system, which will have greater reliability, efficiency, and broader scientific applications. Specific uses of flow cytometry at the Center include: lymphocyte phenotyping, screening cell lines for reactivity with MAbs, selection of MAbs based on reactivity or lack of reactivity with tumor cell lines and/or normal cells, DNA cell cycle analysis, apoptosis studies, detection of tumor cells in stem cell preparations, analyses of dendritic cells, and absolute cell counting for toxicity evaluations in therapy studies. Administrative/scientific oversight for the instrument, including day-to- day management and technical training for in-house staff will be the responsibility of Dr. Stein, under advisement of the Center's Basic Research Committee. We estimate that the major users will require approximately 75-80% of the total usage of the instrument. In addition, the instrument will be available to less frequent users within CMMI as well as users outside of CMMI, including members of the Biological Science Department at Rutgers Newark which is located a short distance from CMMI.